Systems and methods for treating substrates with cryogenic fluid mixtures

ABSTRACT

Disclosed herein are systems and methods for treating the surface of a microelectronic substrate, using a cryogenic fluid mixture used to treat an exposed surface of the microelectronic substrate. The fluid mixture may be expanded through a nozzle to form an aerosol spray or gas cluster jet (GCJ) spray may impinge the microelectronic substrate and remove particles from the microelectronic substrate&#39;s surface. The system may include a two-stage gas nozzle that expands the high pressure incoming gas within two inline expansion chambers. However, in other embodiments, the system may include a single stage nozzle design with one expansion component.

RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationNo. 62/060,130 filed Oct. 6, 2014 and U.S. Provisional PatentApplication No. 62/141,026 filed Mar. 31, 2015, the contents of whichare incorporated herein by reference in their entirety.

FIELD OF USE

This disclosure relates to an apparatus and method for treating thesurface of a microelectronic substrate, and in particular for removingobjects from the microelectronic substrate using cryogenic fluids.

BACKGROUND

Advances in microelectronic technology have cause integrated circuits(ICs) to be formed on microelectronic substrates (e.g., semiconductorsubstrates) with ever increasing density of active components. ICmanufacturing may be carried out by the application and selectiveremoval of various materials on the microelectronic substrate. Oneaspect of the manufacturing process may include exposing the surface ofthe microelectronic substrate cleaning treatments to remove processresidue and/or debris (e.g., particles) from the microelectronicsubstrate. Various dry and wet cleaning techniques have been developedto clean microelectronic substrates.

However, the advances of microelectronic IC manufacturing have led tosmaller device features on the substrate. The smaller device featureshave made the devices more susceptible to damage from smaller particlesthan in the past. Hence, any techniques that enable the removal ofsmaller particles, and/or relatively larger particles, without damagingthe substrate would be desirable.

SUMMARY

Described herein are several apparatus and methods that may use avariety of different fluids or fluid mixtures to remove objects (e.g.,particles) from microelectronic substrates. In particular, the fluid orfluid mixtures may be exposed to the microelectronic substrate in amanner that may remove particles from a surface of the microelectronicsubstrate. The fluid mixtures may include, but are not limited to,cryogenic aerosols and/or gas cluster jet (GCJ) sprays that may beformed by the expansion of the fluid mixture from a high pressure (e.g.,greater than atmospheric pressure) environment to a lower pressureenvironment (e.g., sub-atmospheric pressure) that may include themicroelectronic substrate.

The embodiments described herein have demonstrated unexpected results byimproving particle removal efficiency for sub-100 nm particles withoutdiminution of larger (e.g., >100 nm) particle removal efficiency and/orwithout damaging microelectronic substrate features during particleremoval. The damage reduction may have been enabled by avoidingliquification or reducing (e.g., <1% by weight) liquification of thefluid mixture prior to expansion.

Additional unexpected results included demonstrating a wider cleaningarea (˜100 mm) from a single nozzle. One enabling aspect of the widercleaning area has been shown to be based, at least in part, onminimizing the gap distance between the nozzle and the microelectronicsubstrate. The increased cleaning area size may reduce cycle time andchemical costs. Further, one or more unique nozzles may be used tocontrol the fluid mixture expansion that may be used to remove particlesfrom the microelectronic substrate.

According to one embodiment, an apparatus for treating the surface of amicroelectronic substrate via impingement of the surface with at leastone fluid is described. The apparatus may include: a treatment chamberdefining an interior space to treat a microelectronic substrate with atleast one fluid within the treatment chamber; a movable chuck thatsupports the substrate within the treatment chamber, the substratehaving an upper surface exposed in a position for treatment by the atleast one fluid; a substrate translational drive system operativelycoupled to the movable chuck and configured to translate the movablechuck between a substrate load position and at least one processingposition at which the substrate is treated with the at least one fluid;a substrate rotational drive system operatively coupled to the treatmentchamber and configured to rotate the substrate; and at least one fluidexpansion component (e.g., nozzle) connected to at least one fluidsupply and arranged within the treatment chamber in a manner effectiveto direct a fluid mixture towards the upper surface of the substratewhen the movable chuck is positioned in the at least one processingposition and supports the substrate.

According to one embodiment, an apparatus for treating the surface of amicroelectronic substrate via impingement of the surface with at leastone fluid is described. The apparatus may include: a treatment chamberdefining an interior space to treat a microelectronic substrate with atleast one fluid within the treatment chamber; a movable chuck thatsupports the substrate within the treatment chamber, the substratehaving an upper surface exposed in a position for treatment by the atleast one fluid; a substrate translational drive system operativelycoupled to the movable chuck and configured to translate the movablechuck between a substrate load position and at least one processingposition at which the substrate is treated with the at least one fluid;a substrate rotational drive system operatively coupled to the treatmentchamber and configured to rotate the substrate; and at least one fluidexpansion component (e.g., nozzle) connected to at least one fluidsupply and arranged within the treatment chamber in a manner effectiveto direct a fluid mixture towards the upper surface of the substratewhen the movable chuck is positioned in the at least one processingposition and supports the substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate embodiments of the invention and,together with a general description of the invention given above, andthe detailed description given below, serve to explain the invention.Additionally, the left most digit(s) of a reference number identifiesthe drawing in which the reference number first appears.

FIG. 1 includes a schematic illustration of a cleaning system and across-section illustration of a process chamber of the cleaning systemaccording to at least one embodiment of the disclosure.

FIGS. 2A and 2B include cross-section illustrations of a two-stage gasnozzles according to at least two embodiments of the disclosure.

FIG. 3 includes a cross-section illustration of a single stage gasnozzle according to at least one embodiment of the disclosure.

FIG. 4 includes a cross-section illustration of a flush gas nozzleaccording to at least one embodiment of the disclosure.

FIG. 5 includes an illustration of a gap distance between the gas nozzleand a microelectronic substrate according to at least one embodiment ofthe disclosure.

FIGS. 6A-6B includes illustrations of phase diagrams providing anindication of the process conditions that may maintain a cryogenic fluidin a liquid state or a gas state according to at least one embodiment ofthe disclosure.

FIG. 7 includes a flow chart presenting a method of treating amicroelectronic substrate with a fluid according to various embodiments.

FIG. 8 includes a flow chart presenting another method of treating amicroelectronic substrate with a fluid according to various embodiments.

FIG. 9 includes a flow chart presenting another method of treating amicroelectronic substrate with a fluid according to various embodiments.

FIG. 10 includes a flow chart presenting another method of treating amicroelectronic substrate with a fluid according to various embodiments.

FIG. 11 includes a flow chart presenting another method of treating amicroelectronic substrate with a fluid according to various embodiments.

FIG. 12 includes a flow chart presenting another method of treating amicroelectronic substrate with a fluid according to various embodiments.

FIG. 13 includes a bar chart of particle removal efficiency improvementbetween a non-liquid-containing fluid mixture and liquid-containingfluid mixture according to various embodiments.

FIG. 14 includes particle maps of microelectronic substrates thatillustrate a wider cleaning area based, at least in part, on a smallergap distance between a nozzle and the microelectronic substrate.

FIG. 15 includes pictures of microelectronic substrate features thatshow different feature damage differences between previous techniquesand techniques disclosed herein.

DETAILED DESCRIPTION OF SEVERAL EMBODIMENTS

Methods for selectively removing objects from a microelectronicsubstrate are described in various embodiments. One skilled in therelevant art will recognize that the various embodiments may bepracticed without one or more of the specific details, or with otherreplacement and/or additional methods, materials, or components. Inother instances, well-known structures, materials, or operations are notshown or described in detail to avoid obscuring aspects of variousembodiments of the disclosure. Similarly, for purposes of explanation,specific numbers, materials, and configurations are set forth to providea thorough understanding of the systems and method. Nevertheless, thesystems and methods may be practiced without specific details.Furthermore, it is understood that the various embodiments shown in thefigures are illustrative representations and are not necessarily drawnto scale, except for FIGS. 6A & 6B.

Reference throughout this specification to “one embodiment” or “anembodiment” means that a particular feature, structure, material, orcharacteristic described in connection with the embodiment is includedin at least one embodiment of the invention, but do not denote that theyare present in every embodiment. Thus, the appearances of the phrases“in one embodiment” or “in an embodiment” in various places throughoutthis specification are not necessarily referring to the same embodimentof the invention. Furthermore, the particular features, structures,materials, or characteristics may be combined in any suitable manner inone or more embodiments. Various additional layers and/or structures maybe included and/or described features may be omitted in otherembodiments.

“Microelectronic substrate” as used herein generically refers to theobject being processed in accordance with the invention. Themicroelectronic substrate may include any material portion or structureof a device, particularly a semiconductor or other electronics device,and may, for example, be a base substrate structure, such as asemiconductor substrate or a layer on or overlying a base substratestructure such as a thin film. Thus, substrate is not intended to belimited to any particular base structure, underlying layer or overlyinglayer, patterned or unpatterned, but rather, is contemplated to includeany such layer or base structure, and any combination of layers and/orbase structures. The description below may reference particular types ofsubstrates, but this is for illustrative purposes only and notlimitation. In addition to microelectronic substrates, the techniquesdescribed herein may also be used to clean reticle substrates that maybe used to patterning of microelectronic substrates usingphotolithography techniques.

Cryogenic fluid cleaning is a technique used to dislodge contaminants byimparting sufficient energy from aerosol particles or gas jet particles(e.g., gas clusters) to overcome the adhesive forces between thecontaminants and the microelectronic substrate. Hence, producing orexpanding cryogenic fluid mixtures (e.g., aerosols spray and/or gascluster jet spray) of the right size and velocity may be desirable. Themomentum of the aerosols or clusters is a function of mass and thevelocity. The momentum may be increased by increasing velocity or mass,which may be important to overcome the strong adhesive forces betweenthe particle and the surface of the substrate especially when theparticle may be very small (<100 nm).

In order to influence the velocity of a cryogenic fluid, a carrier gas,comprised of atoms/molecules of relatively smaller or larger atomicweight, can be incorporated into the fluid mixture and enhance thecleaning of the contaminants on the substrate. The carrier gas may ormay not be cryogenically cooled with the remainder of fluid mixture. Thecarrier gas will supply a partial pressure in addition to the partialpressure of the primary cryogen mixture. The partial pressure and gastemperature may be adjusted to place the fluid mixture in liquid/gasstate or gas state to enhance the cleaning ability of the system. Thistechnique satisfies a growing need in the semiconductor industry toenhance cleaning of substrates with small contaminates that traditionalaerosol techniques are limited due to insufficient kinetic energy.

FIG. 1 includes a schematic illustration of a cleaning system 100 thatmay be used to clean microelectronic substrates using aerosol sprays orgas cluster jet (GCJ) sprays and a cross section illustration 102 of theprocess chamber 104 where the cleaning takes place. The aerosol spray orGCJ spray may be formed by expanding cryogenically cooled fluid mixturesinto a sub-atmospheric environment in the process chamber 104. As shownin FIG. 1, one or more fluid sources 106 may provide pressurizedfluid(s) to a cryogenic cooling system 108 prior to being expandedthrough a nozzle 110 in the process chamber 102. The vacuum system 112may be used to maintain the sub atmospheric environment in the processchamber 104 and to remove the fluid mixture as needed.

In this application, one or more of the following variables may beimportant to removing objects from the microelectronic substrate:pressures and temperatures of the incoming fluid mixture in the nozzle110 prior to expansion, the flow rate of the fluid mixture, thecomposition and ratio of the fluid mixture and the pressure in theprocess chamber 104. Accordingly, a controller 112 may be used to storethe process recipes in memory 114 and may use a computer processor 116to issue instructions over a network 118 that controls variouscomponents of the cleaning system 100 to implement the cleaningtechniques disclosed herein.

A person of ordinary skill in the art semiconductor processing may beable to configure the fluid source(s) 106, cryogenic cooling system, thevacuum system 134 and their respective sub-components (not shown, e.g.,sensors, controls, etc.) to implement the embodiments described herein.For example, in one embodiment, the cleaning system 100 components maybe configured to provide pressurized fluid mixtures between 50 psig and800 psig. The temperature of the fluid mixture may be maintained in therange of 70 K and 270 K, but preferably between 70 K and 150K, bypassing the fluid mixture through a liquid nitrogen dewar of thecryogenic cooling system 108. The vacuum system 134 may be configure tomaintain the process chamber 104 at a pressure that may be less than 35Torr to enhance the formation of aerosols and/or gas clusters, or morepreferably less than 10 Torr.

The pressurized and cooled fluid mixture may be expanded into theprocess chamber 104 through the nozzle 110 that may direct the aerosolspray or GCJ spray towards the microelectronic substrate 118. At leastone nozzle 110 may be supported within the process chamber 104, with thenozzle 110 having at least one nozzle orifice that directs the fluidmixture towards the microelectronic substrate 118. For example, in oneembodiment, the nozzle 110 may be a nozzle spray bar that has aplurality of openings along the length of the nozzle spray. The nozzle110 may be adjustable so that the angle of the fluid spray impinging onthe microelectronic substrate 118 can be optimized for a particulartreatment. The microelectronic substrate 118 may secured to a movablechuck 122 that provides at least one translational degree of freedom124, preferably along the longitudinal axis of the vacuum chamber 120,to facilitate linear scanning at least a portion of microelectronicsubstrate 128 through the fluid spray emanating from the nozzle 110. Themovable chuck may be coupled to the substrate translational drive system128 that may include one or more slides and guiding mechanisms to definethe path of movement of the movable chuck 122, and an actuatingmechanism may be utilized to impart the movement to the movable chuck122 along its guide path. The actuating mechanism may comprise anyelectrical, mechanical, electromechanical, hydraulic, or pneumaticdevice. The actuating mechanism may be designed to provide a range ofmotion sufficient in length to permit movement of the exposed surface ofthe microelectronic substrate 118 at least partly through the area offluid spray emanating from the at least one nozzle 110. The substratetranslational drive system 128 may include a support arm (not shown)arranged to extend through a sliding vacuum seal (not shown) in a wallof vacuum chamber 120, wherein a first distal end is mounted to themovable chuck 122 and a second distal end is engaged with an actuatormechanism located outside the vacuum chamber 120.

Furthermore, the movable chuck 122 may also include a substraterotational drive system 130 that may provide at least one rotationaldegree of freedom 126, preferably about an axis normal to the exposedsurface of the microelectronic substrate 118, to facilitate rotationalindexing of the microelectronic substrate 118 from a firstpre-determined indexed position to a second pre-determined indexedposition that exposes another portion of the microelectronic substrate118 to the fluid spray. In other embodiments, the moveable chuck 122 mayrotate at a continuous speed without stopping at any indexed position.Additionally, the movable chuck 122 may vary the angle of incidence withthe fluid spray by changing the position of the microelectronicsubstrate 118, in conjunction with varying the angle of the nozzle 110,or just by itself.

In another embodiment, the movable chuck 122 may include a mechanism forsecuring the microelectronic substrate 118 to an upper surface of themovable chuck 122 during impingement of the at least one fluid spray onthe exposed surface of the microelectronic substrate 118. Themicroelectronic substrate 118 may be affixed to the movable chuck 122using mechanical fasteners or clamps, vacuum clamping, or electrostaticclamping, for example as might be practiced by a person of ordinaryskill in the art of semiconductor processing.

Furthermore, the movable chuck 122 may include a temperature controlmechanism to control a temperature of the microelectronic substrate 118at a temperature elevated above or depressed below ambient temperature.The temperature control mechanism can include a heating system (notshown) or a cooling system (not shown) that is configured to adjustand/or control the temperature of movable chuck 122 and microelectronicsubstrate 118. The heating system or cooling system may comprise are-circulating flow of heat transfer fluid that receives heat frommovable chuck 122 and transfers heat to a heat exchanger system (notshown) when cooling, or transfers heat from the heat exchanger system tomovable chuck 122 when heating. In other embodiments, heating/coolingelements, such as resistive heating elements, or thermo-electricheaters/coolers can be included in the movable chuck 122.

As shown in FIG. 1, the process chamber 102 may include a dual nozzleconfiguration (e.g., second nozzle 132) that may enable the processingof the substrate 118 using a cryogenic aerosol and/or a GCJ spray or acombination thereof within the same vacuum chamber 120. However, thedual nozzle configuration is not required. Some examples of nozzle 110design will be described in the descriptions of FIGS. 2A-4. Although thenozzles 110,132 are shown to be positioned in a parallel manner they arenot required to be parallel to each other to implement the cleaningprocesses. In other embodiments, the nozzles 110,132 may be at oppositeends of the treatment chamber 120 and the movable chuck 122 may move thesubstrate 118 into a position that enables one or more of the nozzles110,132 to spray a fluid mixture onto the microelectronic substrate 118.

In another embodiments, the microelectronic substrate 118 may be moved,such that the exposed surface area (e.g., area that include theelectronic devices) of the microelectronic substrate 118 may be impingedby the fluid mixture (e.g., aerosol or GCJ) provided from the firstnozzle 110 and/or the second nozzle 132 at the same or similar time(e.g., parallel processing) or at different times (e.g., sequentialprocessing). For example, the cleaning process may include an aerosolcleaning process followed by a GCJ cleaning processes or vice versa.Further, the first nozzle 110 and the second nozzle 132 may bepositioned so their respective fluid mixtures impinge themicroelectronic substrate 118 at different locations at the same time.In one instance, the substrate 118 may be rotated to expose the entiremicroelectronic substrate 118 to the different fluid mixtures.

The nozzle 110 may be configured to receive low temperature (e.g.,<273K) fluid mixtures with inlet pressures (e.g., 50 psig-800 psig)substantially higher than the outlet pressures (e.g., <35 Torr. Theinterior design of the nozzle 110 may enable the expansion of the fluidmixture to generate solid and/or liquid particles that may be directedtowards the microelectronic substrate 118. The nozzle 110 dimensions mayhave a strong impact on the characteristics of the expanded fluidmixture and range in configuration from simple orifice(s) arranged alonga spray bar, multi-expansion volume configurations, to single expansionvolume configurations. FIGS. 2A-4 illustrate several nozzle 110embodiments that may be used. However, the scope of the disclosure maynot be limited to the illustrated embodiments and the methods disclosedherein may apply to any nozzle 110 design. As noted above, the nozzle110 figures may not be drawn to scale.

FIG. 2A includes a cross-section illustration of a two-stage gas nozzle200 that may include two gas expansion regions that may be in fluidcommunication with each other and may subject the fluid mixture topressure changes as the fluid mixture progresses through the two-stagegas (TSG) nozzle 200. The first stage of the TGS nozzle 200 may be areservoir component 202 that may receive the fluid mixture through aninlet 204 that may be in fluid communication with the cryogenic coolingsystem 108 and the fluid sources 106. The fluid mixture may expand intothe reservoir component 202 to a pressure that may be less than theinlet pressure. The fluid mixture may flow through a transition orifice206 to the outlet component 208. In some embodiments, the fluid mixturemay be compressed to a higher pressure when it flows through thetransition orifice 206. The fluid mixture may expand again into theoutlet component 208 and may contribute to the formation of an aerosolspray or gas cluster jet as the fluid mixture is exposed to the lowpressure environment of the vacuum chamber 120 via the outlet orifice210. Broadly, the TGS nozzle 200 may incorporate any dimension designthat may enable a dual expansion of the fluid mixture between the inletorifice 204 and the outlet orifice 210. The scope of TGS nozzle 200 maynot be limited to the embodiments described herein.

In the FIG. 2A embodiment, the reservoir component 202 may include acylindrical design that extends from the inlet orifice 204 to thetransition orifice 206. The cylinder may have a diameter 212 that mayvary from the size of the transition orifice 206 to more than threetimes the size of the transition orifice 206.

In one embodiment, the TGS nozzle 200 may have an inlet orifice 204diameter that may range between 0.5 mm to 3 mm, but preferably between0.5 mm and 1.5 mm. The reservoir component 208 may comprise a cylinderwith a diameter 212 between 2 mm and 6 mm, but preferably between 4 mmand 6 mm. The reservoir component 208 may have a length 214 between 20mm and 50 mm, but preferably between 20 mm and 25 mm. At the non-inletend of the reservoir component 208 may transition to a smaller diameterthat may enable the fluid mixture to be compressed through thetransition orifice 206 into the outlet component 208.

The transition orifice 206 may exist in several different embodimentsthat may be used to condition the fluid mixture as it transitionsbetween the reservoir component 202 and the outlet component 208. In oneembodiment, the transition orifice 206 may be a simple orifice oropening at one end of the reservoir component 202. The diameter of thistransition orifice 206 may range between 2 mm and 5 mm, but preferablybetween 2 mm and 2.5 mm. In another embodiment, as shown in FIG. 2A, thetransition orifice 206 may have a more substantial volume than thesimple opening in the previous embodiment. For example, the transitionorifice 206 may have a cylindrical shape that may be constant along adistance that may be less than 5 mm. In this embodiment, the diameter ofthe transition orifice 206 may be larger than the initial diameter ofthe outlet component 208. In this instance, a step height may existbetween the transition orifice 206 and the outlet component 208. Thestep height may be less than 1 mm. In one specific embodiment, the stepheight may be about 0.04 mm. The outlet component 208 may have a conicalshape that increases in diameter between the transition orifice 206 andthe outlet orifice 208. The conical portion of the outlet component 208may have a half angle between 3° and 10°, but preferably between 3° and6°.

FIG. 2B illustrates another embodiment 220 of the TGS nozzle 200 thatincludes a reservoir component 202 with a diameter 218 that is about thesame size as the transition orifice 206. In this embodiment, thediameter 218 may be between 2 mm to 5 mm with a length 214 similar tothe FIG. 2A embodiment. The FIG. 2B embodiment may reduce the pressuredifference between the reservoir component 202 and the outlet component208 and may improve the stability of the fluid mixture during the firststage of the TGS nozzle 200. However, in other embodiments, a singlestage nozzle 300 may be used to reduce the pressure fluctuations in theTSG nozzle 200 embodiment and may reduce the turbulence of the fluidmixture.

FIG. 3 illustrates a cross-section illustration of one embodiment of asingle stage gas (SSG) nozzle 300 that may incorporate a singleexpansion chamber between the inlet orifice 302 and the outlet orifice304. The SSG nozzle 300 expansion chamber may vary, but in the FIG. 3embodiment illustrates a conical design that may have an initialdiameter 306 (e.g., 1.5 mm-3 mm) that may be slightly larger than theinlet orifice 302 (e.g., 0.5 mm-1.5 mm). The conical design may includea half angle between 3° and 10°, but preferably between 3° and 6°. Thehalf angle may be the angle between an imaginary center line throughexpansion chamber of the SSG nozzle 300 (from the inlet orifice 302 andoutlet orifice 304) and the sidewall of the expansion chamber (e.g.,conical wall). Lastly, the SSG nozzle 300 may have length between 18 mmand 40 mm, preferably between 18 mm and 25 mm. Another variation of theSSG nozzle 300 may include a continuous taper of the expansion volumefrom the inlet orifice 302 to the outlet orifice 304, as illustrated inFIG. 4.

FIG. 4 includes a cross-section illustration of a flush gas (FG) nozzle400 that may include a continuous expansion chamber that does notinclude any offsets or constrictions between the inlet orifice 402 andthe outlet orifice 404. As the name suggests, the initial diameter ofthe expansion volume may be flush with the inlet diameter 402, which maybe between 0.5 mm to 3 mm, but preferably between 1 mm and 1.5 mm. Inone embodiment, the outlet diameter 404 may be between 2 mm and 12 mm,but preferably between two times to four times the size of the inletdiameter 402. Further, the half angle may be between 3° and 10°, butpreferably between, but preferably between 3° and 6°. The length 406 ofthe expansion volume should vary between 10 mm and 50 mm between theinlet orifice 402 and the outlet orifice 404. Additionally, thefollowing embodiments may apply to both the FIG. 3 and FIG. 4embodiments. In one specific embodiment, the nozzle may have conicallength of 20 mm, a half angle of 3° and an outlet orifice diameter ofabout 4 mm. In another specific embodiment, the conical length may bebetween 15 mm and 25 mm with an outlet orifice diameter between 3 mm and6 mm. In another specific embodiment, the outlet orifice diameter may beabout 4 mm with an inlet diameter of about 1.2 mm and a conical lengthof about 35 mm.

Another feature that may impact the cleaning efficiency of the cleaningsystem 100 may be the distance between the nozzle outlet 404 and themicroelectronic substrate 118. In some process embodiments, the gapdistance may impact the cleaning efficiency not only by the amount ofparticles removed, but also the amount of surface area that theparticles may be removed during a single pass across the substrate 118.In some instances, the aerosol spray or GCJ spray may be able to clean alarger surface area of the substrate 118 when the outlet orifice of thenozzle 110 may be closer (e.g., <50 mm) to the microelectronic substrate119.

FIG. 5 includes an illustration 500 of a gap distance 502 between theoutlet orifice 404 of a nozzle 110 and the microelectronic substrate 118according to at least one embodiment of the disclosure. In one instance,the gap distance 502 may be measured from the end of the nozzle 110assembly that forms the structure or support for the nozzle 110. Inanother instance, the gas distance 502 may be measured from a plane thatextends across the largest diameter of the conical expansion region thatis exposed to the microelectronic substrate 118.

The gap distance 502 may vary depending on the chamber pressure, gascomposition, fluid mixture temperature, inlet pressure, nozzle 110design or some combination thereof. Generally, the gap distance 502 maybe between 2 mm and 50 mm. Generally, the vacuum chamber 120 pressuremay be at less than 35 Torr to operate within the 2 mm and 50 mm gapdistances 502. However, when the chamber pressure may be at less than 10Torr and the gas nozzle 110 has an outlet orifice less than 6 mm, thegap distance 502 may be optimized to be less than 10 mm. In somespecific embodiments, a desirable gap distance 502 may be about 5 mm fora nozzle 110 that has an outlet diameter less than 5 mm and the vacuumchamber 120 pressure being at less than 10 Torr.

In other embodiments, the gap distance 502 may be based, at least inpart, on an inverse relationship with the vacuum chamber 120 pressure.For example, the gap distance 502 may be less than or equal to a valuederived by dividing a constant value by the chamber 120 pressure. In oneembodiment, the constant may be a dimensionless parameter or in units ofmm*Torr and the vacuum chamber 120 pressure may be measured in Torr, seeequation 1:Gap Distance</=Constant/Chamber Pressure  (1)

In this way, the value obtained by dividing the constant by the chamberpressure provides a gap distance 502 that may be used for the cleaningprocess. For example, in one specific embodiment, the constant may be 50and the chamber pressure may be about 7 Torr. In this instance, the gapdistance would be less than or about 7 mm under the equation (1). Inother embodiments, the constant may range between 40 and 60 and thepressure may range from 1 Torr to 10 Torr. In another embodiment, theconstant may range between 0.05 to 0.3 and the pressure may range from0.05 Torr to 1 Torr. Although gap distance 502 may have a positiveimpact on cleaning efficiency, there are several other process variablesthat can contribute to cleaning efficiency using aerosol spray and gascluster jet spray.

The hardware described in the descriptions of FIGS. 1-5 may be used toenable the aerosol spray and gas cluster jet (GCJ) spray with slightvariations in hardware and more substantive changes for processconditions. The process conditions may vary between different fluidmixture compositions and ratios, inlet pressures, inlet temperatures, orvacuum chamber 120 pressures. One substantive difference between theaerosol spray and the GCJ spray processes may be the phase compositionof the incoming fluid mixtures to the nozzle 110. For example, theaerosol spray fluid mixture may have a higher liquid concentration thanthe GCJ fluid mixture, which may exist in gaseous state with very littleor no liquid in the incoming GCJ fluid mixture to the nozzle 110.

In the aerosol spray embodiment, the temperature in the cryogeniccooling system 108 may be set to a point where at least a portion of theincoming fluid mixture to the nozzle 110 may exist in a liquid phase. Inthis embodiment, the nozzle mixture may be at least 10% by weight in aliquid state. The liquid/gas mixture is then expanded at a high pressureinto the process chamber 104 where the cryogenic aerosols may be formedand may include a substantial portion of solid and/or liquid particles.However, the state of the fluid mixtures may not be the sole differencebetween the aerosol and GCJ processes, which will be described ingreater detail below.

In contrast, the incoming GCJ spray fluid mixture to the nozzle 110 maycontain very little (e.g., <1% by volume) or no liquid phase and may bein a completely gaseous state. For example, the temperature in thecryogenic cooling system 108 may be set to a point that prevents thefluid mixture from existing in a liquid phase for the GCJ cleaningprocess. Accordingly, phase diagrams may be one way to determine theprocess temperatures and pressures that may be used to enable theformation of an aerosol spray or GCJ spray in the process chamber 104.

Turning to FIGS. 6A-6B, the phase diagrams 600, 608 may indicate whichphase the components of the incoming fluid mixture may exist or morelikely to include a liquid phase, gas phase, or a combination thereof.An argon phase diagram 602, a nitrogen phase diagram 604, an oxygenphase diagram 610, and a xenon phase diagram 612 illustrated for thepurposes of explanation and illustration of exemplary phase diagrams. Aperson of ordinary skill in the art may be able to find phase diagraminformation in the literature or via the National Institutes ofStandards and Technology of Gaithersburg, Md. or other sources. Theother chemicals described herein may also have a representative phasediagrams, but are not shown here for the purposes of ease ofillustration.

The phase diagrams 600, 608 may be represented by a graphicalrepresentation that highlights the relationship between pressure (e.g.,y-axis) and temperature (e.g., x-axis) and the likelihood that theelement may exist in a gaseous or liquid state. The phase diagrams mayinclude a gas-liquid phase transition line 606 (or a vapor-liquidtransition line) that may represent where the element may transitionbetween a liquid state or a gaseous state. In these embodiments, theliquid phase may be more likely to be present when the pressure andtemperature of the elements are to the left of the gas-liquid transitionline 606 and the gaseous phase may predominate when the pressure andtemperature of the elements are to the right of the gas-liquidtransition line 606. Further, when the pressure and temperature of theelement is very close to the gas-liquid phase transition line 606, thelikelihood that the element may exist in a gas and liquid phase ishigher than when the pressure and temperature may be further away fromthe gas-liquid phase transition line 606. For example, in view of theargon phase diagram 602, when argon is held at a pressure of 300 psi ata temperature of 100K the argon is more likely to include portion thatis in the liquid phase or have a higher concentration (by weight) ofliquid than when the argon is maintained at a pressure of 300 psi at atemperature of 130K. The liquid concentration of argon may increase asthe temperature decreases from 130K while maintaining a pressure of 300psi. Likewise, the argon liquid concentration may also increase when thepressure increases from 300 psi while maintaining a temperature of 130K.Generally, per the phase diagrams 600, to maintain argon in a gaseousstate, the temperature should be above 83K and to maintain nitrogen in agaseous state the temperature should be above 63K. However, the phase ofany nitrogen-argon mixture may be dependent upon the relativeconcentration of the elements, as well as the pressure and temperatureof the fluid mixture. However, the phase diagrams 600 may be used asguidelines that may provide an indication of the phase of theargon-nitrogen fluid mixture or at least the likelihood that liquid maybe present. For example, for an aerosol cleaning process the incomingfluid mixture may have a temperature or pressure that may on or to theleft of the gas-liquid transition line 606 for one or more of theelements of the incoming fluid mixture. In contrast, a GCJ cleaningprocess may be more likely to use an incoming fluid mixture that mayhave a pressure and temperature that may be to the right of thegas-liquid phase transition line 606 for one or more of the elements inthe GCJ incoming fluid mixture. In some instances, the system 100 mayalternate between an aerosol process and a GCJ process by varying theincoming temperature and/or pressure of the fluid mixture.

It should be noted that the gas-liquid phase transition line 606 aresimilar to each of the phase diagrams 600, 608, however their values maybe unique to the chemical assigned to each of the phase diagrams 600,608, but the phase diagrams 600, 608 may be used by a person of ordinaryskill in the art as described in the explanation of the argon phasediagram 602. A person of ordinary skill in the art may use the phasediagrams 600, 608 to optimize the amount of liquid and/or gas in thefluid mixture of the aerosol or GCJ sprays.

A cryogenic aerosol spray may be formed with a fluid or fluid mixturebeing subjected to cryogenic temperatures at or near the liquefyingtemperature of at least one of the fluids and then expanding the fluidmixture through the nozzle 110 into a low pressure environment in theprocess chamber 104. The expansion conditions and the composition of thefluid mixture may have a role in forming small liquid droplets and/orsolid particles which comprise the aerosol spray that may impinge thesubstrate 118. The aerosol spray may be used to dislodge microelectronicsubstrate 118 contaminants (e.g., particles) by imparting sufficientenergy from the aerosol spray (e.g., droplets, solid particles) toovercome the adhesive forces between the contaminants and themicroelectronic substrate 118. The momentum of the aerosol spray mayplay an important role in removing particles based, at least in part, onthe amount of energy that may be needed to the aforementioned adhesiveforces. The particle removal efficiency may be optimized by producingcryogenic aerosols that may have components (e.g., droplets, crystals,etc.) of varying mass and/or velocity. The momentum needed to dislodgethe contaminants is a function of mass and velocity. The mass andvelocity may be very important to overcome the strong adhesive forcesbetween the particle and the surface of the substrate, particularly whenthe particle may be very small (<100 nm).

FIG. 7 illustrates a flow chart 700 for a method of treating amicroelectronic substrate 118 with a cryogenic aerosol to removeparticles. As noted above, one approach to improving particle removalefficiency may be to increase the momentum of the aerosol spray.Momentum may be the product of the mass and velocity of the aerosolspray contents, such that the kinetic energy may be increased byincreasing mass and/or velocity of the components of the aerosol spray.The mass and/or velocity may be dependent upon a variety of factors thatmay include, but are not limited to, fluid mixture composition, incomingfluid mixture pressure and/or temperature, and/or process chamber 104temperature and/or pressure. The flow chart 700 illustrates oneembodiment that optimizes momentum by using a various combinations ofnitrogen and/or argon and at least one other a carrier gas.

Turning to FIG. 7, at block 702, the system 100 may receive themicroelectronic substrate 118 in a process chamber 104. Themicroelectronic substrate 118 may include a semiconductor material(e.g., silicon, etc.) that may be used to produce an electronic devicesthat may include, but are not limited to, memory devices, microprocessordevices, light emitting displays, solar cells and the like. Themicroelectronic substrate 118 may include patterned films or blanketfilms that may include contamination that may be removed by an aerosolcleaning process implemented on the system 100. The system 100 mayinclude the process chamber 104 that may be in fluid communication witha cryogenic cooling system 108 and one or more fluid sources 106. Theprocess chamber may also include a fluid expansion component (e.g., TSGnozzle 200, etc.) that may be used to expand a fluid mixture to form theaerosol spray to clean the microelectronic substrate 118.

At block 704, the system 100 may supply a fluid mixture to a fluidexpansion component via the cryogenic cooling system 108 that may coolthe fluid mixture to less than 273K. In one embodiment, the temperatureof the fluid mixture may be greater than or equal to 70K and less thanor equal to 200K, more particularly the temperature may be less than130K. The system 100 may also maintain the fluid mixture at a pressuregreater than atmospheric pressure. In one embodiment, the fluid mixturepressure may be maintained between 50 psig and 800 psig.

In one embodiment, the fluid mixture may include a first fluidconstituent comprising molecules with an atomic weight less than 28 andat least one additional fluid constituent comprising molecules with anatomic weight of at least 28. A person of ordinary skill in the artwould be able to optimize the fluid mixture of two or more fluids toachieve a desired momentum for the aerosol spray components to maximizeparticle removal efficiency or to target different types or sizes ofparticles. In this instance, the first fluid constituent may include,but is not limited to, helium, neon or a combination thereof. The atleast one additional fluid constituent may include, but is not limitedto, nitrogen (N₂), argon, krypton, xenon, carbon dioxide, or acombination thereof. In one specific embodiment, the additional fluidconstituent comprises an N₂ and argon mixture and the first fluidconstituent may include helium. However, the temperature, pressure andconcentration of the fluid mixture may vary to provide different typesof aerosol sprays. In other embodiments, the phase or state of the fluidmixture, which may include, gas, liquid, gas-liquid at variousconcentrations that will be described below.

The ratio between the first fluid constituent and the additional fluidconstituents may vary depending on the type of spray that may be desiredto clean the microelectronic substrate 118. The fluid mixture may varyby chemical composition and concentration and/or by phase or state ofmatter (e.g., gas, liquid, etc.). In one aerosol embodiment, the firstfluid constituent may comprise at least 50% by weight of the fluidmixture that may include a first portion in a gaseous state and a secondportion in a liquid state. In most instances, the fluid mixture may havebe least 10% by weight being in a liquid phase. The fluid mixture may beoptimized to address different types and/or size of particles that maybe on patterned or patterned microelectronic substrates 118. Oneapproach to alter the particles removal performance may be to adjust thefluid mixture composition and/or concentration to enhance particleremoval performance. In another fluid mixture embodiment, the firstfluid constituent comprises between 10% and 50% by weight of the fluidmixture. In another embodiment, the first fluid constituent may includebetween 20% and 40% by weight of the fluid mixture. In another fluidmixture embodiment, the first fluid constituent may include between 30%and 40% by weight of the fluid mixture. The phase of the aforementionedaerosol fluid mixtures may also vary widely to adjust for differenttypes of particles and films on the substrate 118. For example, thefluid mixture may include a first portion that may be in a gaseous stateand a second portion that may be in a liquid state.

In one embodiment, the second portion may be at least 10% by weight ofthe fluid mixture. However, in certain instances, a lower concentrationof liquid may be desirable to remove particles. In the lower liquidconcentration embodiment, the second portion may be no more than 1% byweight of the fluid mixture. The liquid portion of the fluid mixture mayinclude liquid phases or one or more gases that may comprise the fluidmixture. In these fluid mixture embodiments, the system 110 mayimplement the aerosol spray by flowing between 120 slm and 140 slm ofthe additional fluid constituent and 30 slm and 45 slm of the firstfluid constituent.

In addition to incoming pressure, concentration, and composition of thefluid mixture, the momentum and composition of the aerosol spray mayalso be impacted by the pressure in the process chamber 102. Morespecifically, the chamber pressure may impact the mass and/or velocityof the liquid droplets and/or solid particles in the aerosol spray. Theexpansion of the fluid mixture may rely on a pressure difference acrossthe nozzle 110.

At block 706, the system 100 may provide the fluid mixture into theprocess chamber 104 such that at least a portion of the fluid mixturewill contact the microelectronic substrate 118. The expansion of thefluid mixture via the fluid expansion component (e.g., nozzle 110) mayform the liquid droplets and/or solid particles of the aerosol spray.The system 100 may maintain the process chamber 104 at a chamberpressure of 35 Torr or less. In certain instances, it may be desirableto maintain the process chamber 104 at much lower pressure to optimizethe mass and/or velocity of the liquid droplets and/or solid particlesin the aerosol spray. In one specific embodiment, particle removalcharacteristics of the aerosol spray may be more desirable for certainparticles when the process chamber is maintained at less than 10 Torr.It was also noted, the particle removal efficiency covered a largersurface area when the process chamber 104 is maintained at less than 5Torr during fluid mixture expansion.

When the fluid mixture flows through the fluid expansion component thefluid mixture may undergo a phase transition related to the expansion ofthe fluid mixture from a relatively high pressure (e.g., >atmosphericpressure) to a relatively low pressure (e.g., <35 Torr). In oneembodiment, the incoming fluid mixture may exist in a gaseous orliquid-gas phase and be under relatively higher pressure than theprocess chamber 102. However, when the fluid mixture flows through orexpands into the low pressure of the process chamber 104, the fluidmixture may begin to transition to form liquid droplets and/or a solidstate as described above. For example, the expanded fluid mixture maycomprises a combination of portions in a gas phase, a liquid phase,and/or a solid phase. This may include what may be referred to above acryogenic aerosol. In yet another embodiment, the fluid mixture may alsoinclude a gas cluster. In one embodiment, may be an agglomeration ofatoms or molecules by weak attractive forces (e.g., van der Waalsforces). In one instance, gas clusters may be considered a phase ofmatter between gas and solid the size of the gas clusters may range froma few molecules or atoms to more than 10⁵ atoms.

In one more embodiment, the fluid mixture may transition between aerosoland gas clusters (e.g., GCJ) in same nozzle while treating the samemicroelectronic substrate 118. In this way, the fluid mixture maytransition between an aerosol and GCJ by going from higher liquidconcentration to a lower liquid concentration in the fluid mixture.Alternatively, the fluid mixture may transition between the GCJ and theaerosol by going from lower liquid concentration to a higher liquidconcentration in the fluid mixture. As noted above in the description ofFIG. 6A-6B, the liquid phase concentration may be controlled bytemperature, pressure or a combination thereof. For example, in theaerosol to GCJ transition the fluid mixture liquid concentration maytransition from 10% by weight to less than 1% by weight, in one specificembodiment. In another specific embodiment, the GCJ to aerosoltransition may occur when the fluid mixture's liquid concentrationtransitions from 1% by weight to less than 10% by weight. However, thetransition between aerosol and GCJ, and vice versa, may not be limitedpercentages in the aforementioned specific embodiments and are merelyexemplary for the purposes of explanation and not limitation.

At block 708, the expanded fluid may be directed towards themicroelectronic substrate 118 and may remove particles themicroelectronic substrate 118 as the fluid expansion component movesacross the surface of the microelectronic substrate 118. In someembodiments, the system 100 may include a plurality of fluid expansioncomponents that may be arranged around the microelectronic substrate118. The plurality of fluid expansion components may be usedconcurrently or serially to remove particles. Alternatively, some of thefluid expansion components may be dedicated to aerosol processing andthe remaining fluid expansion components may be used for GCJ processing.

In addition to aerosol processing, microelectronic substrates 118 mayalso be cleaned using GCJ processing. Cryogenic gas clusters may beformed when a gaseous species, such as argon or nitrogen or mixturesthereof, is passed through a heat exchanger vessel, such as a dewar(e.g., cryogenic cooling system 108), that subjects the gas to cryogenictemperatures that may be above the liquification temperature of any ofthe gas constituents. The high pressure cryogenic gas may then beexpanded through a nozzle 110 or an array of nozzles angled orperpendicular with respect to the surface of the microelectronicsubstrate 118. The GCJ spray may be used to remove particles from thesurface of the semiconductor wafer without causing any damage orlimiting the amount of damage to the microelectronic substrate's 118surface.

Gas clusters, which may be an ensemble or aggregation of atoms/moleculesheld together by forces (e.g., van der waals forces), are classified asa separate phase of matter between atoms or molecules in a gas and thesolid phase and can range in size from few atoms to 10⁵ atoms. TheHagena empirical cluster scaling parameter (Γ*) given in Equation (2),provides the critical parameters that may affect cluster size. The termk is condensation parameter related to bond formation (a gas speciesproperty); d is the nozzle orifice diameter, a is the expansion halfangle and P_(o) and T_(o) are the pre-expansion pressure and temperaturerespectively. Nozzle geometries that have a conical shape help constrainthe expanding gas and enhance the number of collisions between atoms ormolecules for more efficient cluster formation. In this way, the nozzle110 may enhance the formation of clusters large enough to dislodgecontaminants from the surface of the substrate 118. The GCJ sprayemanating from the nozzle 110 may not be ionized before it impinges onthe substrate 118 but remains as a neutral collection of atoms.

$\begin{matrix}{\Gamma^{*} = {k\frac{\left( \frac{d}{\tan\;\alpha} \right)^{0.85}}{T_{o}^{2.29}}P_{o}}} & (2)\end{matrix}$

The ensemble of atoms or molecules that comprise the cluster may have asize distribution that can provide better process capability to targetcleaning of contaminants of sizes less than 100 nm due to the proximityof the cryogenic cluster sizes to the contaminant sizes on themicroelectronic substrate 118. The small size of the cryogenic clustersimpinging on the microelectronic substrate 118 may also prevent orminimize damaging of the microelectronic substrate 118 which may havesensitive structures that need to be preserved during the treatment.

As with the aerosol process, the GCJ process may use the same or similarhardware described in description of the system 100 of FIG. 1 and itscomponents described in the description in FIGS. 2-5. However, theimplementation of the GCJ methods are not limited to the hardwareembodiments described herein. In certain embodiments, the GCJ processmay use the same or similar process conditions as the aerosol process,but the GCJ process may have a lower liquid phase concentration for thefluid mixture. However, the GCJ processes are not required to have alower liquid concentration than all of the aerosol process embodimentsdescribed herein. A person of ordinary skill in the art may implement aGCJ process that increases the amount or density of gas clustersrelative to any liquid droplets and/or solid particles (e.g., frozenliquid) that may exist in the GCJ methods described herein. Those GCJmethods may have several different techniques to optimize the cleaningprocess and a person of ordinary skill in the art may use anycombination of these techniques to clean any microelectronic substrate118. For example, a person of ordinary skill in the art may vary thenozzle 110 design and/or orientation, the fluid mixture's composition,concentration or composition, the fluid mixture's incoming pressureand/or temperature and the process chamber's 104 pressure and/ortemperature to clean microelectronic substrates 118.

FIG. 8 provides a flow chart 800 for a cryogenic method for generating aGCJ process to remove particles from a microelectronic substrate 118. Inthis embodiment, the method may be representative of a GCJ process thatmay use a multi-stage nozzle 100, similar to the two-stage gas (TSG)nozzle 200 described herein in the description of FIGS. 2A-2B. The FIG.8 embodiment may reflect the pressure differences or changes of thefluid mixture as it transitions from a high pressure environment to alow pressure environment through the multi-stage nozzle 110.

Turning to FIG. 8, at block 802, the system 100 may receive themicroelectronic substrate 118 in a vacuum process chamber 104 that mayinclude a fluid expansion component (e.g., TSG nozzle 200). The systemmay place the process chamber 104 to sub-atmospheric condition prior toexposing the microelectronic substrate 118 to any fluid mixturesprovided by the cryogenic cooling system 108.

At block 804, the system 100 may supply or condition the fluid mixtureto be at a temperature less than 273K and a pressure that may be greaterthan atmospheric pressure. For example, the fluid mixture temperaturemay be between 70K and 200K or more particularly between 70K and 120K.The fluid mixture pressure may be between 50 psig and 800 psig. Ingeneral, at least a majority (by weight) of the fluid mixture may be inthe gas phase. However, in other embodiments, the fluid mixture may beless than 10% (by weight) in the gas phase, and more particularly may beless than 1% (by weight) in the gas phase.

The fluid mixture may be a single fluid composition or a combination offluids that may include, but are not limited to, N₂, argon, xenon,helium, neon, krypton, carbon dioxide or any combination thereof. Aperson of ordinary skill in the art may choose one or more combinationsof the aforementioned fluids to treat the substrate using one fluidmixture at a time or a combination of fluid mixtures for the samemicroelectronic substrate 118.

In one embodiment, the fluid mixture may include a combination of N₂ andargon at a ratio between 1:1 and 11:1. A person of ordinary skill in theart may optimize the ratio in conjunction with the liquid concentrationof the N₂ and/or the argon to remove particles from the microelectronicsubstrate 118. However, in other embodiments, a person of ordinary skillin the art may also optimize the energy or momentum of the GCJ fluidmixture to optimize particle removal efficiency. For example, the fluidmixture may include another carrier gas that may alter the mass and/orvelocity of the GCJ process. The carrier gases may include, but are notlimited to, xenon, helium, neon, krypton, carbon dioxide or anycombination thereof. In one embodiment, the fluid mixture may include a1:1 to 4:1 mixture of N2 to argon that may be mixed one or more of thefollowing carrier gases: xenon, krypton, carbon dioxide or anycombination thereof. In other instances, the carrier gas composition andconcentration may be optimized with different ratios of N2 and argonwith different ratios of the carrier gases. In other embodiments, thecarrier gases may be included based on the Hagena value, k as shown inTable 1.

TABLE 1 Gas N₂ O₂ CO₂ CH₄ He Ne Ar Kr Xe k 528 1400 3660 2360 3.85 1.851650 2890 5500

In general, for some embodiments, the lower the k value fluid should beequal or higher in concentration when being mixed with N₂, argon or acombination thereof. For example, when the carrier gases are mixed withN₂, argon, or a combination thereof (e.g., 1:1 to 4:1) the ratio betweenN₂, argon, or a combination thereof should be done using a ratio mixtureof at least 4:1 when using xenon, helium, neon, krypton, carbon dioxideor any combination thereof with up to a ratio mixture of 11:1. Incontrast, when helium or neon or combined with N₂, argon, or acombination thereof (e.g., 1:1 to 4:1). The ratio mixture may be atleast 1:4 between N₂, argon, or a combination thereof (e.g., 1:1 to 4:1)and helium, neon or combination thereof. The aforementioned combinationsof N2, argon and/or the carrier gases may also apply to the otheraerosol and GCJ methods described herein.

At block 806, the system 110 may provide the fluid mixture to the fluidexpansion component from the fluid source 106 and/or from the cryogeniccooling system 108. The system 100 may also maintain the process chamber104 at a pressure less than 35 Torr. For example, the system 100 may usethe vacuum system 134 to control the process chamber 104 pressure priorto or when the fluid mixture may be introduced to the process chamber104. In some embodiments, the process chamber 104 pressure may between 5Torr-10 Torr and in some embodiments the pressure may be less than 5Torr.

The GCJ spray may be formed when the fluid mixture transitions between ahigher pressure environment (e.g., upstream of the nozzle 110) and a lowpressure environment (e.g., process chamber). In the FIG. 8 embodiment,the fluid expansion component may be the TSG nozzle 200 that may placethe fluid mixture under at least two pressure changes or expansionsprior to impinging the microelectronic substrate 118.

At block 808, the fluid mixture may expand through the inlet orifice 204into the reservoir component 202 and achieve or maintain a reservoirpressure into the reservoir component 202 that is greater than theprocess chamber 104 pressure and less than the incoming pressure of thefluid mixture. Broadly, the reservoir pressure may be less than 800 psigand greater than or equal to 35 Torr. But, the reservoir pressure 202may fluctuate due to the gas flow variations within the confined spacesillustrated in FIGS. 2A-2B.

The fluid mixture may proceed to the transition orifice 206 which may ormay not be smaller than the diameter of the reservoir component 202.When the transition orifice 206 is smaller than the reservoir component202 diameter, the fluid mixture may be compressed to a higher pressurewhen flowing to or through the transition orifice 206 into the outletcomponent 208 of the TSG nozzle 200.

At block 810, the fluid mixture may be maintained at an outlet pressurein the outlet component 210 of the fluid expansion component. The outletpressure may be greater than the chamber pressure and less than thereservoir component 202 pressure. During the transition between thetransition orifice 206 and the outlet orifice 210 the fluid mixture mayexpand and may form gas clusters as described above. The difference inpressure between the outlet component 210 and the process chamber 102may be due to the smaller confined volume of the outlet component 210compared to the larger volume of the process chamber 104.

The gas clusters may be directed towards the outlet orifice 210 and thefluid mixture may continue to expand after the fluid mixture exits theTSG nozzle 200. However, the momentum may direct at least a majority ofthe gas cluster spray towards the microelectronic substrate 118. Asnoted above, the size of the gas cluster may vary between a few atoms upto 10⁵. The process may be optimized to control the number of gasclusters and their size by varying by the aforementioned processconditions. For example, a person of ordinary skill in the art may alterthe incoming fluid mixture pressure, fluid mixturecomposition/concentration, process chamber 102 pressure or anycombination thereof to remove particles from the microelectronicsubstrate 118.

At block 812, the components of the GCJ spray may be used to kineticallyor chemically remove objects or contaminants from the microelectronicsubstrate 118. The objects may be removed via the kinetic impact of theGCJ spray and/or any chemical interaction of the fluid mixture may havewith the objects. However, the removal of the objects is not limited tothe theories of kinetic and/or chemical removal and that any theory thatmay be used to explain their removal is applicable, in that the removalof the objects after applying the GCJ spray may be sufficient evidencefor any applicable theory that may be used to explain the objectsremoval.

The relative position of the TSG nozzle 200 and the microelectronicsubstrate 118 may also be used to optimize object removal. For example,the angle of incidence of the GCJ spray may be adjusted by moving theTSG nozzle 200 between 0° and 90° between the surface of the of themicroelectronic substrate 118 the plane of the outlet orifice 210. Inone specific embodiment, the angle of incidence may be between 30° and60° to remove objects based on the composition or pattern on themicroelectronic substrate 118. Alternatively, the angle of incidence maybe between 60° and 90°, and more particularly about 90°. In otherembodiments, more than one nozzle 110 may be used to treat themicroelectronic substrate 118 at similar or varying angles of incidence.

In the aforementioned removal embodiments, the microelectronic substrate118 may also be translated and/or rotated during the removal process.The removal speed may be optimized to a desired dwell time of the GCJspray over particular portions of the microelectronic substrate 118. Aperson of ordinary skill in the art may optimize the dwell time and GCJspray impingement location to achieve a desired particle removalefficiency. For example, a desirable particle removal efficient may begreater than 80% removal between pre and post particle measurements.

Similarly, the gap distance between the outlet orifice 210 and a surfaceof the microelectronic substrate 118 may be optimized to increaseparticle removal efficiency. The gap distance is described in greaterdetail in the description of FIG. 5, but generally the gap distance maybe less than 50 mm.

The GCJ process may also be implemented using single stage nozzles 300,400 similar to those described in the descriptions of FIGS. 3 & 4. Thesingle stage nozzles 300, 400 may include a single expansion chamberthat may be continuous, in that the diameter 306 of the expansion regionis the same or increasing between the inlet orifice 302 and the outletorifice 304. For example, the single stage nozzles 300, 400 may not havea transition orifice 206 like the TSG nozzle 200. However, the singlestage GCJ methods may also be used by the TSG nozzle 200 systems 100 andare not limited to single stage nozzle systems 100. Likewise, themethods described in the descriptions of FIGS. 9-12 may also be used bysingle stage nozzles 300, 400.

FIG. 9 illustrates a flow chart 900 for another method of treating amicroelectronic substrate 118 with a GCJ spray. The positioning of thenozzle 110, relative to the microelectronic substrate 118, may have astrong impact on the particle removal efficiency. Particularly, the gapdistance between the outlet orifice 304 and a surface of themicroelectronic substrate 118 may have an impact on particle removalefficiency. The gap distance may have influence on the fluid flow anddistribution of the GCJ spray and may impact the size of cleaningsurface area by the nozzle 110. In this way, the cycle time for GCJprocess may be reduced due to fewer passes or lower dwell times for thenozzle 110.

Turning to FIG. 9, at block 902, the microelectronic substrate 118 maybe received in the process chamber 104 that may include a gas expansioncomponent (GEC) (e.g., nozzle 300, 400). The GEC may be any of thenozzles 110 described herein, but may particularly be configured thesame or similar to the TSG nozzles 200, the SSG nozzle 300 or the Flushnozzle 400. Generally, the nozzles may include an inlet orifice 402 toreceive the fluid mixture and an outlet orifice 404 that flows the fluidmixture into the process chamber 104.

At block 904, the system 100 may position the microelectronic substrate118 opposite of the GEC, such that the outlet orifice 404 disposed aboveor adjacent to the microelectronic substrate 118. The GEC may be also bepositioned at an angle relative to the surface of the microelectronicsubstrate 118. The surface being the portion where the microelectronicdevices are manufactured. The angle may range between 0° and 90°. TheGEC positioning may also be optimized based on the gap distance 502 asdescribed in FIG. 5. The gap distance 502 may have an impact on the flowdistribution towards and/or across the microelectronic substrate 118. Asthe gap distance 502 increases the cleaning surface area may decreaseand may require additional nozzle passes to maintain or improve particleremoval efficiency. The speed of the expanded fluid mixture may alsovary depending on the gap distance 502. For example, the fluid flowlaterally across the microelectronic substrate 118 may increase when thegap distance 502 is decreased. In some embodiments, the higher velocitymay provide higher particle removal efficiency.

Generally, the GEC may likely be within 50 mm of the microelectronicsubstrate's 118 surface. But, in most embodiments, the gap distance 502may be less than 10 mm for the aerosol or GCJ processes describedherein. In one specific embodiment, the gap distance 502 may be about 5mm prior to dispensing the fluid mixture through the GEC into theprocess chamber 104.

At block 906, the system 100 may supply the fluid mixture to the GEC ata temperature that may less than 273K and at a pressure that preventsliquid formation in the fluid mixture at the provided temperature of thefluid mixture. In this way, the liquid concentration within the fluidmixture may be non-existent or at least less than 1% by weight of thefluid mixture. A person of ordinary skill in the art of chemicalprocessing may be able to use any known techniques to measure the liquidconcentration of the fluid mixture. Further, the person of ordinaryskill in the art may be able to select the proper combination oftemperature and pressure using the phase diagrams 600, 608 or any otherknown phase diagram literature that may be available for a singlespecies or a mixture of species.

In one embodiment, the temperature may be greater than or equal to 70Kand less than 273K fluid mixture that may include nitrogen, argon,xenon, helium, carbon dioxide, krypton or any combination thereof.Likewise, the pressure may be selected using the phase diagrams 600, 608or by any other known measurement technique that minimizes the amount ofliquid concentration to less than 1% by weight in the fluid mixture. Inmost embodiments, the pressure may be less than or equal to 10 Torr,however in other embodiments, the pressure may be greater than 10 Torrto maximize particle removal efficiency.

At block 908, the system may provide the fluid mixture into the processchamber 104 through the GEC such that at least a portion of the fluidmixture will contact the microelectronic substrate 118. As noted above,the fluid mixture may expand from a relatively high pressure to a lowpressure in the process chamber 104. In one embodiment, the processchamber 104 may be maintained at a chamber pressure of 35 Torr or less.

In one embodiment, the fluid mixture may include a combination of N₂ andargon at a ratio between 1:1 and 11:1, particularly at ratio less than4:1. In other embodiments, the fluid mixture may include another carriergas that may alter the mass and/or velocity of the GCJ spray. Thecarrier gases may include, but are not limited to, xenon, helium, neon,krypton, carbon dioxide or any combination thereof. In one embodiment,the fluid mixture may include a 1:1 to 4:1 mixture of N₂ to argon thatmay be mixed one or more of the following carrier gases: xenon, krypton,carbon dioxide or any combination thereof.

For example, when the carrier gases are mixed with N₂, argon, or acombination thereof (e.g., 1:1 to 4:1) the ratio between N₂ and argon,or a combination thereof should be done using a ratio mixture of atleast 4:1 when using xenon, krypton, carbon dioxide or any combinationthereof with up to a ratio mixture of 11:1. In contrast, when helium orneon or combined with N₂, argon, or a combination thereof (e.g., 1:1 to4:1). The ratio mixture may be at least 1:4 between N₂, argon, or acombination thereof (e.g., 1:1 to 4:1) and helium, neon or combinationthereof. The aforementioned combinations of N2, argon and/or the carriergases may also apply to the other aerosol and GCJ methods describedherein.

In another embodiment, the fluid mixture may include N2 combined withhelium or neon and at least one of the following gases: argon, krypton,xenon, carbon dioxide. In one specific embodiment, the mixture ratio theaforementioned combination may be 1:2:1.8.

At block 910, the expanded fluid mixture (e.g., GCJ spray) may beprojected towards the microelectronic substrate 118 and contacts theobjects (e.g., kinetic and/or chemical interaction) on the surface, suchthe objects may be removed from the microelectronic substrate 118. Thekinetic and/or chemical interaction of the GCJ spray may overcome theadhesive forces between the objects and the microelectronic substrate118. The objects may be removed from the process chamber 104 via thevacuum system 134 or deposited elsewhere within the process chamber 104.

FIG. 10 illustrates another flow chart 1000 for another method fortreating a microelectronic substrate 118 with a cryogenic fluid. In thisembodiment, the fluid mixture may generate a GCJ spray that may have arelatively low liquid concentration. As noted above, the temperature andpressure of the fluid mixture may have an impact on how much liquid (byweight) may be in the fluid mixture. In this instance, the liquidconcentration of the fluid mixture may be optimized by varying thetemperature.

Turning to FIG. 10, at block 1002 the microelectronic substrate 118 maybe received in the process chamber 104 that may include a gas expansioncomponent (GEC) (e.g., nozzle 300, 400). The GEC may be any of thenozzles 110 described herein, but may particularly be configured thesame or similar to the TSG nozzles 200, the SSG nozzle 300 or the Flushnozzle 400. Generally, the nozzles may include an inlet orifice 402 toreceive the fluid mixture and an outlet orifice 404 that flows the fluidmixture into the process chamber 104.

At block 1004, the system 100 may position the microelectronic substrate118 opposite of the GEC, such that the outlet orifice 404 disposed aboveor adjacent to the microelectronic substrate 118. The GEC may be also bepositioned at an angle relative to the surface of the microelectronicsubstrate 118. The surface being the portion where the microelectronicdevices are manufactured. The angle may range between 0° and 90°. TheGEC positioning may also optimized based on the gap distance 502 asdescribed in FIG. 5. Generally, the GEC may likely be within 50 mm ofthe microelectronic substrate's 118 surface. But, in most embodiments,the gap distance 502 may be less than 20 mm for the aerosol or GCJprocesses described herein. In one specific embodiment, the gap distance502 may be about 5 mm prior to dispensing the fluid mixture through theGEC into the process chamber 104.

At block 1006, the system 110 may supplying the fluid mixture to the FECat a pressure greater than atmospheric pressure and at a temperaturethat is less than 273K and greater than a condensation temperature ofthe fluid mixture at the given pressure. The condensation temperaturemay vary between different gases and may vary between different gasmixtures with different compositions and concentrations. A person ofordinary skill in the art may be able to determine the gas condensationtemperature for the fluid mixture using known literature (e.g., phasediagrams) or empirical techniques based, at least in part, onobservation and/or measurement of the fluid mixture using knowntechniques.

In one instance, the condensation temperature, at a given pressure, maythe temperature at which a fluid may transition exist in a liquid phase.For example, for a fluid mixture being held above the condensationtemperature indicates the fluid mixture may exist in a gaseous statewithout any liquid phase being present or with a very small amount ofliquid (e.g., <1% by weight). In most embodiments, the fluid mixturetemperature may vary between 50K and 200K, but more particularly between70K and 150K depending on the fluid mixture composition which includegases with different condensation temperatures.

For example, in a N₂ fluid mixture embodiment, the amount of liquid byweight may be estimated by using the N2 phase diagram 604. For anincoming pressure of about 100 psi, the temperature of the fluid mixturemay be greater than 100K to minimize the amount of liquid. The fluidmixture, in this embodiment, may not have any liquid, or at least beless than 1% by weight, when the incoming temperature is about 120K witha pressure of 100 psi.

At block 1008, the system 100 may provide the fluid mixture into theprocess chamber 104 through the GEC, such that at least a portion of thefluid mixture will contact the microelectronic substrate 118. In thisembodiment, the process chamber 104 pressure may at leastsub-atmospheric, but more particularly less than 10 Torr.

In one embodiment, the fluid mixture may include a combination of N₂ andargon at a ratio between 1:1 and 11:1, particularly at ratio less than4:1. In other embodiments, the fluid mixture may include another carriergas that may alter the mass and/or velocity of the GCJ spray. Thecarrier gases may include, but are not limited to, xenon, helium, neon,krypton, carbon dioxide or any combination thereof. In one embodiment,the fluid mixture may include a 1:1 to 4:1 mixture of N₂ to argon thatmay be mixed one or more of the following carrier gases: xenon, krypton,carbon dioxide or any combination thereof.

For example, when the carrier gases are mixed with N₂, argon, or acombination thereof (e.g., 1:1 to 4:1) the ratio between N₂ and argon,or a combination thereof should be done using a ratio mixture of atleast 4:1 when using xenon, krypton, carbon dioxide or any combinationthereof with up to a ratio mixture of 11:1. In contrast, when helium orneon or combined with N₂, argon, or a combination thereof (e.g., 1:1 to4:1). The ratio mixture may be at least 1:4 between N₂, argon, or acombination thereof (e.g., 1:1 to 4:1) and helium, neon or combinationthereof. The aforementioned combinations of N2, argon and/or the carriergases may also apply to the other aerosol and GCJ methods describedherein.

At block 1010, the expanded fluid mixture (e.g., GCJ spray) may beprojected towards the microelectronic substrate 118 and contacts theobjects (e.g., kinetic and/or chemical interaction) on the surface, suchthe objects may be removed from the microelectronic substrate 118. Thekinetic and/or chemical interaction of the GCJ spray may overcome theadhesive forces between the objects and the microelectronic substrate118. The objects may be removed from the process chamber 104 via thevacuum system 134 or deposited elsewhere within the process chamber 104.

FIG. 11 illustrates a flow chart 1100 for another method for treating amicroelectronic substrate 118 with a cryogenic fluid. In thisembodiment, the fluid mixture may generate a GCJ spray that may have arelatively low liquid concentration. As noted above, the temperature andpressure of the fluid mixture may have an impact on how much liquid (byweight) may be in the fluid mixture. In this instance, the liquidconcentration of the fluid mixture may be optimized by varying thepressure. Further, the gap distance 502 may be determined using thecontroller 112 to use a calculation using the recipe pressure and aconstant value that will be described below.

Turning to FIG. 11, at block 1102 the microelectronic substrate 118 maybe received in the process chamber 104 that may include a gas expansioncomponent (GEC) (e.g., nozzle 300). The GEC may be any of the nozzles110 described herein, but may particularly be configured the same as orsimilar to the TSG nozzles 200, the SSG nozzle 300 or the Flush nozzle400. Generally, the nozzles may include an inlet orifice 402 to receivethe fluid mixture and an outlet orifice 404 that flows the fluid mixtureinto the process chamber 104.

At block 1104, the system 100 may supply a gas mixture to the GEC at anincoming temperature less than 273K and an incoming pressure thatprevents liquid from forming in the gas mixture at the incomingtemperature. For example, in an N₂ embodiment, the N₂ phase diagram 604indicates that a fluid mixture at about 100K would likely have apressure less than 100 psi to maintain the N₂ in gaseous phase. If thepressure was about 150 psi or higher, there would be a strongerprobability that the liquid phase may be present in the N₂ process gas.

At block 1106, the system 100 may provide the fluid mixture into theprocess chamber 104 through the GEC, such that at least a portion of thefluid mixture will contact the microelectronic substrate 118. In thisembodiment, the process chamber 104 pressure may at leastsub-atmospheric, but more particularly less than 10 Torr.

In one embodiment, the fluid mixture may include a combination of N₂ andargon at a ratio between 1:1 and 11:1, particularly at ratio less than4:1. In other embodiments, the fluid mixture may include another carriergas that may alter the mass and/or velocity of the GCJ spray. Thecarrier gases may include, but are not limited to, xenon, helium, neon,krypton, carbon dioxide or any combination thereof. In one embodiment,the fluid mixture may include a 1:1 to 4:1 mixture of N₂ to argon thatmay be mixed one or more of the following carrier gases: xenon, krypton,carbon dioxide or any combination thereof.

For example, when the carrier gases are mixed with N₂, argon, or acombination thereof (e.g., 1:1 to 4:1) the ratio between N₂ and argon,or a combination thereof should be done using a ratio mixture of atleast 4:1 when using xenon, krypton, carbon dioxide or any combinationthereof with up to a ratio mixture of 11:1. In contrast, when helium orneon or combined with N₂, argon, or a combination thereof (e.g., 1:1 to4:1). The ratio mixture may be at least 1:4 between N₂, argon, or acombination thereof (e.g., 1:1 to 4:1) and helium, neon or combinationthereof. The aforementioned combinations of N2, argon and/or the carriergases may also apply to the other aerosol and GCJ methods describedherein.

At block 1108, the system 110 may position the microelectronic substrate118 at a gap distance 502 between the outlet (e.g., outlet orifice 404)and the microelectronic substrate 118. The gap distance 502 being based,at least in part, on a ratio of the chamber pressure and a constantparameter with a value between 40 and 60, as shown in equation 1 in thedescription of FIG. 5. In one embodiment, the units of the constantparameter may have units of be length/pressure (e.g., mm/Torr).

At block 1110, the expanded fluid mixture may be projected towards themicroelectronic substrate 118 and contacts the objects (e.g., kineticand/or chemical interaction) on the surface, such the objects may beremoved from the microelectronic substrate 118. The kinetic and/orchemical interaction of the GCJ spray may overcome the adhesive forcesbetween the objects and the microelectronic substrate 118. The objectsmay be removed from the process chamber 104 via the vacuum system 134 ordeposited elsewhere within the process chamber 104.

FIG. 12 illustrates a flow chart 1200 for another method for treating amicroelectronic substrate 118 with a cryogenic fluid. In thisembodiment, the fluid mixture may generate a GCJ spray that may have arelatively low liquid concentration. As noted above, the temperature andpressure of the fluid mixture may have an impact on how much liquid (byweight) may be in the fluid mixture. In this instance, the system 100may maintain a ratio between the incoming fluid mixture pressure and thechamber pressure 104 to optimize the momentum or composition (e.g., gascluster, etc.). Additionally, the system 100 may also optimize theincoming fluid mixture pressure to control the liquid concentration ofthe incoming fluid mixture within the confines of the pressure ratiorelationship between the incoming pressure and the process chamber 104pressure.

Turning to FIG. 12, at block 1202 the microelectronic substrate 118 maybe received in the process chamber 104 that may include a gas expansioncomponent (GEC) (e.g., nozzle 300,400). The GEC may be any of thenozzles 110 described herein, but may particularly be configured thesame as or similar to the TSG nozzles 200, the SSG nozzle 300 or theFlush nozzle 400. Generally, the nozzles may include an inlet orifice402 to receive the fluid mixture and an outlet orifice 404 that flowsthe fluid mixture into the process chamber 104.

At block 1204, the system 100 may supplying the fluid mixture to thevacuum process chamber 104 and the system 100 may maintain the fluidmixture at a temperature and/or pressure that maintains the fluidmixture in a gas phase. The fluid mixture may include, but is notlimited to, at least one of the following gases: nitrogen, argon, xenon,krypton, carbon oxide or helium.

In another embodiment, the fluid mixture may include N₂ combined with atleast helium or neon and with at least one of the following gases:argon, krypton, xenon, carbon dioxide. In one specific embodiment, theratio of the aforementioned fluid mixture combination may be about1:2:2. In another more specific embodiment, the ratio of theaforementioned fluid mixture may be 1:2:1.8.

At block 1206, the system 100 may maintain the process chamber 104pressure and the incoming fluid mixture pressure using a pressure ratio.In this way, the system 100 may insure that there may be a balance orrelationship between the incoming pressure and the process pressure(e.g., ratio=(incoming pressure/process pressure). The pressure ratiomay be a threshold value that may or may not be exceed or the pressureratio may include a range that may be maintained despite changes toincoming pressure or chamber pressure. The pressure ratio value mayrange between 200 and 500,000. However, the pressure ratio may act athreshold that may or may not be exceed or designate a range that may bemaintained given the recipe conditions stored in the controller 112. Inthis way, the pressure difference across the nozzle may be controlled tomaintain GCJ/Aerosol spray momentum or composition (e.g., gas clustersize, gas cluster density, solid particle size, etc.).

In the pressure ratio embodiments, the values are in view of similarunit, such that the controller 112 may convert the pressures to the sameor similar units to control the incoming and chamber pressures.

The upper threshold embodiments may include a pressure ratio that maynot be exceed, such that the incoming pressure over the chamber pressuremay be less than the upper threshold ratio. For example, the upperthreshold values may be one of the following values: 300000, 5000, 3000,2000, 1000 or 500.

In another embodiment, the controller 112 may maintain the incoming andprocess pressure to be within a range of the pressure ratio values.Exemplary ranges may include, but are not limited to: 100000 to 300000,200000 to 300000, 50000 to 100000, 5000 to 25000, 200 to 3000, 800 to2000, 500 to 1000 or 700 to 800.

At block 1208, the system 110 may position the microelectronic substrate118 at a gap distance 502 between the outlet (e.g., outlet orifice 404)and the microelectronic substrate 118. The gap distance 502 being based,at least in part, on a ratio of the chamber pressure and a constantparameter with a value between 40 and 60, as shown in equation 1 in thedescription of FIG. 5. In one embodiment, the units of the constantparameter may have units of be length/pressure (e.g., mm/Torr).

At block 1210, the expanded fluid mixture may be projected towards themicroelectronic substrate 118 and contacts the objects (e.g., kineticand/or chemical interaction) on the surface, such the objects may beremoved from the microelectronic substrate 118. The kinetic and/orchemical interaction of the GCJ spray may overcome the adhesive forcesbetween the objects and the microelectronic substrate 118. The objectsmay be removed from the process chamber 104 via the vacuum system 134 ordeposited elsewhere within the process chamber 104.

FIG. 13 includes a bar chart 1300 of particle removal efficiencyimprovement between a non-liquid-containing fluid mixture (e.g., GCJ)and liquid-containing fluid mixture (e.g., aerosol). One of theunexpected results disclosed herein relates to improved particleefficiency for sub-100 nm particles and maintaining, or improving,particle removal efficiency for particles greater than 100 nm. Previoustechniques may include treating microelectronic substrates withcryogenic fluid mixtures that have a liquid concentration greater than10%. Newer techniques that generated the unexpected results may includetreating microelectronic substrates 118 with cryogenic fluid mixturesthat have no liquid concentration (by weight) or a liquid concentrationless than 1%.

In the FIG. 13 embodiment, microelectronic substrates 118 were depositedwith silicon nitride particles using a commercially available depositionsystem. The silicon nitride particles had a similar density and sizesfor both tests. The baseline cryogenic process (e.g., liquidconcentration>1% by weight) was applied to at least one microelectronicsubstrate 118 and the GCJ was applied a different group ofmicroelectronic substrates 118 also covered with silicon nitrideparticles. In this instance, the GCJ process include a nitrogen to argonflow ratio of 2:1 with an inlet pressure of 83 psig prior to the nozzle110 which separated the high pressure fluid source from the vacuumchamber that was maintained at about 9 Torr. The nozzle 110 inletdiameter was ˜0.06″. The gas distance 502 was between 2.5-4 mm. Thewafer was passed underneath the nozzle two times such that a regioncontaminated with the particles would be exposed twice to the GCJ spray.The particles were measured before and after processing using a KLA SURFSCAN SP2-XP from KLA-Tencor™ of Milpitas, Calif.

Under previous techniques, as shown in FIG. 13, sub-100 nm particleremoval efficiency (PRE) decreased from greater than 80% for particlesgreater than 90 nm down to less than 30% for particles less than 42 nm.Specifically, the PRE dropped from ˜87% (@>90 nm particles) to ˜78% forparticles between 65 nm to 90 nm. The falloff in PRE between 55 nm-65 nmparticles and 40 mn-55 nm was more pronounced. The PRE dropped to ˜61%and ˜55%, respectively. Lastly, the greatest decrease in PRE was seenfor particles less 40 nm, ˜24% PRE.

In view of this data, improvements to sub-100 nm particle efficiencywere expected to exhibit a similar diminishing return with decreasingparticle size. However, the GCJ techniques disclosed herein, not onlyimproved sub-100 nm PRE, but maintained PRE to a higher degree thanexpected. For example, as shown in FIG. 13, GCJ PRE didn't drop below˜80% for any of the particle bin sizes.

As shown in FIG. 13, the GCJ PRE for particles greater than 90 nmimproved to over 95% which is more than a 5% improvement over resultsusing previous techniques. Further, the GCJ process demonstrated greaterability to remove sub-100 nm particles as particle sizes decreased whencompared to previous techniques. For example, the 65 nm-90 nm, 55 nm-65nm and the 40 nm-55 nm bins had at least 90% PRE. The improvementsranging between ˜15% to ˜35% for each bin size. However, the greatestimprovement was for the sub-40 nm bin size with a PRE improvement from25% to ˜82%.

The unexpected results for the GCJ PRE were two-fold. First, theincrease in PRE for particles greater than 90 nm coupled with theincreased PRE for sub-90 nm particles. Second, that the differencebetween the bins sizes for the GCJ process had a much tighterdistribution than the PRE results for the aerosol process using similarranges of process conditions.

FIG. 14 includes particle maps 1400 of microelectronic substrates thatillustrate a wider cleaning area based, at least in part, on a smallergap distance 502 between a nozzle 110 and the microelectronic substrate118. Generally, as gas expands from a high pressure environment into alow pressure environment the gas is more likely to cover a largersurface area, or coverage area, the further gas is away from the initialexpansion point. In this way, the effective cleaning area was thought tobe larger when the gas nozzle was positioned farther away from themicroelectronic substrate 118. However, this was not the case, in facthaving a smaller gap distance 502 achieved a completely counterintuitiveresult to obtaining a wider cleaning area on the microelectronicsubstrate 118.

As shown in the post-cleaning particles maps the 5 mm gap distance has awider cleaning area than the 10 mm gap distance. The 5 mm gap particlemap 1406 shows that for the right half of the microelectronic substrate118, the PRE was ˜70%. In contrast, the 10 mm gap particle map 1408 hada ˜50% PRE for the right half of the 200 mm microelectronic substrate118. In this instance, the 5 mm gap particle map indicates a cleanedarea 1410 that is about 80 mm wide from a nozzle 110 with an outletorifice of no more than 6 mm. It was unexpected that a nozzle 110 withsuch a small outlet orifice would be able to have an effective cleaningdistance more than 12 times its own size.

FIG. 15 includes pictures 1500 of microelectronic substrate featuresthat show different feature damage differences between previoustechniques (e.g., aerosol) and techniques (e.g., GCJ) disclosed herein.The difference in damage is visible to the naked eye and confirmed bycloser inspection by a scanning electron microscope (SEM). In thisembodiment, polysilicon features were formed on the microelectronicsubstrate using known patterning techniques. The features had a width ofabout 20 nm and a height of about 125 nm. Separate feature samples(e.g., line structures) were exposed to processes similar to the aerosoland GCJ processes disclosed herein.

Under the previous techniques, damage to line structures was evidencedby the discoloration in the pictures 1502, 1504 of the microelectronicsubstrate 118 that was exposed to an aerosol cleaning process. Thevisible line damage is corroborated by the aerosol SEM picture 1506. Incontrast, the discoloration is not present in the GCJ pictures 1508,1510 and damage is not shown in the GCJ SEM picture 1512. Accordingly,the lack of discoloration in the GCJ pictures 1508, 1510 and lack ofdamage in the GCJ SEM picture 1512 suggests that the GCJ techniquesdescribed herein are less destructive to the microelectronic substrate118 than the aerosol processes.

Although only certain embodiments of this invention have been describedin detail above, those skilled in the art will readily appreciate thatmany modifications are possible in the embodiments without materiallydeparting from the novel teachings and advantages of this invention.Accordingly, all such modifications are intended to be included withinthe scope of this invention. For example, the embodiments describedabove may be incorporated together and may add or omit portions of theembodiments as desired. Hence, the number of embodiments may not belimited to only the specific embodiments described herein, such that aperson of ordinary skill may craft additional embodiments using theteachings described herein.

What is claimed is:
 1. A substrate cleaning system, comprising: a vacuumprocess chamber comprising a substrate holder for a microelectronicsubstrate that rotates and translates the substrate during a treatment,wherein the vacuum process chamber is at a pressure of 10 Torr or less,and wherein the microelectronic substrate has a surface; a fluiddelivery system comprising a pressurized and cooled cleaning gas,wherein the pressurized and cooled cleaning gas comprises at least oneof argon and nitrogen, and wherein the pressurized and cooled cleaninggas is in a gas phase comprising less than 1 weight percent of a liquidphase and wherein the pressurized and cooled gas is at a temperature inthe range from 70 K to 150 K; a fluid expansion component, the fluidexpansion component comprising: an inlet orifice through which thepressurized and cooled cleaning is introduced into the fluid expansioncomponent; an outlet orifice through which the expanded pressurized andcooled cleaning gas is expanded into the process chamber as a flow ofgas clusters that flows laterally across the substrate surface, whereinthe outlet orifice is positioned to provide a gap distance between theoutlet orifice and the microelectronic substrate in the range from 2 mmto 10 mm, and wherein the angle of incidence between the flow of gasclusters and the substrate surface is between 60 degrees and about 90degrees; a first gas expansion region disposed between the inlet orificeand the outlet orifice in which the pressurized and cooled gas isexpanded in a first expansion stage; and a second gas expansion regiondisposed between the first expansion region and the outlet orifice, thesecond expansion region comprising a cross-sectional geometry that isdifferent from the first expansion region, wherein the pressurized andcooled gas expands further in a second expansion stage to form the gascluster spray, and wherein the second expansion region helps toconstrain the expanding pressurized and cooled gas to form the flow ofthe gas clusters; and a transition orifice between the first gasexpansion region and the second gas expansion region through which thepressurized and cooled gas expands further into the second expansionregion, wherein the transition orifice is smaller than the diameter ofthe first expansion region.
 2. The system of claim 1, wherein thecross-sectional geometry of the second gas expansion region comprises alength-wise cross-section disposed between the first gas expansionregion and the outlet orifice.
 3. The system of claim 1, wherein theinlet orifice comprises an inlet diameter less than or equal to 3 mm andthe outlet orifice comprises an outlet diameter less than or equal to 7mm.
 4. The system of claim 3, wherein the inlet orifice comprises aninlet diameter greater than or equal to 1 mm and less than 3 mm and theoutlet orifice comprises an outlet diameter greater than or equal to 2mm and less than or equal to 7 mm.
 5. The system of claim 1, wherein thesecond expansion region comprises a conical shape that increases indiameter from the inlet diameter at the transition orifice to the outletorifice.
 6. The system of claim 5, wherein the second expansion regioncomprises a half angle less than or equal to 10° .
 7. The system ofclaim 1, wherein the first gas expansion region comprises a lengthbetween 20 mm and 50 mm.
 8. The system of claim 1, wherein the first gasexpansion region comprises a cylindrical shape.
 9. The system of claim8, wherein the first gas expansion region comprises a diameter between 2mm and 6 mm.
 10. The system of claim 8, wherein the first gas expansionregion comprises a cylindrical shape and the second gas expansion regioncomprises a conical shape comprising an inlet diameter that is less thana diameter of the first gas expansion region.
 11. The system of claim 1,wherein the system comprises two or more fluid expansion components. 12.The system of claim 1, wherein the inlet orifice comprises a diameterbetween 1 mm and 3 mm and the outlet orifice comprises a diameterbetween 2 mm and 10 mm.
 13. The system of claim 1, wherein thepressurized and cooled cleaning gas further comprises one or more of thefollowing gases: helium, neon, krypton, xenon, or carbon dioxide. 14.The system of claim 1, wherein the pressurized and cooled cleaning gasincoming to the fluid expansion component is at a temperature andpressure that prevents the gas from existing in a liquid phase.
 15. Thesystem of claim 1, wherein the pressurized and cooled cleaning gascomprises nitrogen.
 16. The system of claim 1, wherein the pressurizedand cooled cleaning gas comprises argon.
 17. The system of claim 1,wherein the pressurized and cooled cleaning gas comprises nitrogen andargon.
 18. The system of claim 1, wherein the transition orifice has acylindrical shape.
 19. The system of claim 1, wherein the transitionorifice is an opening at an end of the first gas expansion region.